Retardation controller



March s, 1938. B, s, MKMAN 2,110,692'

RETARDATION CONTROLLER Filed May l5, 1936 SiIrl I www M I@ yHmm w! l GNIVENTOR EURTDN SAMMAN ATTORN EY I BY Patented Mar. 8, 1938 UNETED STATESTENT oFFlCE RETARDATION CONTROLLER Application May 15, 1936, Serial No.79,939

10 Claims.

My invention relates to retardation controllers for vehicles, andparticularly to retardation controllers for limiting the braking forceof fluid pressure brakes in accordance with the rate of retardation ofthe vehicle.

in vehicles employing friction type brakes it is well known that for agiven braking pressure such brakes are less effective in retarding themotion of the vehicle at high speeds Ythan at ly low speeds because ofthe varying coefficient of friction between the wheels and the brakeshoe vwhich is lower at high speed than at low speed.

In order to bring a vehicle to a stop quickly, employing the maximumpermissible brake pressure at all speeds, it has been usual practice forthe operator to apply the brakes with a high 4degree of braking pressureat high speeds, and, as the speed of the vehicle lessens. to decreasethe braking pressure gradually in order to provide for a smooth stopwithout shock or slipping of the wheels.

It is an object of my invention to provide a reliable and inexpensiveretardation controller device for application to uidkpressure brakeequipment.

It is another object of my invention to provide a retardation controllerdevice that is operable in either direction of Vehicle travel, and thatis not subject to adjustments by the operator. 3 It is a further objectof my invention to provide a retardation controller device that may bedirectly applied to each brake cylinder pipe of the equipment.

Other objects and advantages of my invention will be apparent from thefollowing description of one preferred embodiment of my invention,reference being had to the accompanying drawing, in which Fig. 1 is adiagrammatic view of a brake equipment employing my invention, and

Fig. 2 is an enlarged View of a portion thereof, parts being shown insection.

Referring to the drawing, a fluid pressure brake 45 is provided having abrake cylinder I that may be supplied with fluid under pressure from amain reservoir 2 in accordance with the operation of a brake Valvedevice 3 having a manually operable handle 4 as supplied through a brake50 cylinder pipe 5 to which my retardation controller device 6- isapplied.

It will be understood that Fig. 1 is schematic only and that fluid underpressure may be supplied to the brake cylinder by means of any well 55known equipment such as straight air equipment or automatic equipment,the supply of fluid under pressure being controlled either by a relayvalve device, or an automatic valve device, in the manner well known inthese types of brake equipment.

The retardation controller device 6 is shown attached to and directlysupported by the brake cylinder pipe 5, preferably adjacent to the brakecylinder i, and comprises a casing 'I containing a chamber 3 that issubstantially filled With a 10 heavy mobile liquid, such as mercury. Thefront and rear walls 9 and I I,respectively, of the chamber 8 aremovable abutments, such as diaphragrns, and are provided with followerplates I2 and I3, respectively. The diaphragms 9 and 15 I I constitutethe front and rear walls of the chamber 8, with respect to the directionof travel of the vehicle,l so that, when the brakes are applied, apressure caused by the inertia of the mobile fluid within the chamber 8is exerted di- 20 rectly against either the abutment 9 or the abut-Vment II, depending upon the direction of motion of the vehicle.

A valve piston I4 is positioned within a bor I5 in the lower part of thecasing, providing a 25 valve chamber I6 on one side thereof that is inconstant open communication with the brake cylinder I through passageI'I and brake cylinder pipe 5, and a chamber I8 on the other sidethereof that is in constant open communication with pilot valve chambersI9 and 2|. The piston i4 is normally urged downwardly by' a spring 22contained within the chamber I8, causing a valve 23 thereon to engage avalve seat 24 and 35 close communication between the valve chamber I6and the atmosphere through exhaust port 25j A pilot valve 26 is providedwithin the pilot valve chamber I9 having a stem 2l extending 40 througha bore in a wall of the casing and adapt ed to be engaged by thefollower plate I2 associated with the diaphragm 9. A spring 28 isprovided, one end of which is positioned within a recess provided in thecasing and the other end of which is positioned within a recess in thepilot valve 26, for forcing the pilot valve to itsv seat to closecommunication from the pilot valve chamber I9 to the atmosphere throughchamber 29 and exhaust port 3l. 50

A pilot valve 32 is provided Within the pilot valve chamIber 2l having astem 33 extending through a bore in the casing and adapted to be.engaged by the following plate I3 associated.

with the diaphragm II. A spring 34 is provided 55` having one endpositioned in a recess in the casing structure and the other endpositioned in a recess in the pilot valve 32 for forcing the valve toits seat to close communication between the pilot valve chamber 2l andthe atmosphere through the chamber 35 and the exhaust port 3E.

The operation of the equipment is as follows:

When the operator wishes to apply the brakes the handle il of the brakevalve device 3 is moved to a brake applying position to eect the supplyof iluid under pressure from the reservoir 2 to the brake cylinder I, toa desired degree, and is then moved to lap position, in the well knownmanner. As fluid under pressure lls up in the brake cylinder pipe 5 andthe brake cylinder I, it also builds up in the passage I'I and thechamber I 5 below the valve piston Ill. The spring 22, within thechamber I8, is so adjusted as to hold the piston I4 downwardly causingthe valve 23 to remain against its seat 261 until a predetermineddifferential in pressures between the chambers I6 and I8 exists. As thefluid pressure builds. up in the brake cylinder I and in the chamber I6at the usual rate of application of the brakes, fluid under pressurealso flows from the chamber I through a restricted port 3l in the pistonIll to the chamber I8 to equalize the pressures on the opposite sides ofthe piston III. This flow of iluid under pressure from the chamber It tothe chamber IS takes place at a suliciently rapid rate to prevent thedifferential necessary to unseat the valve 23 from' developing, so thatthe valve 23 is held seated by the spring 22.

It will be appreciated that the device is so mounted that the bore ofthe chamber 3 extends longitudinally of the vehicle so that the endabutments Il and I I constitute the front and rear walls of the chamber8 with respect to the direction of vehicle travel and are subject to theforce of inertia caused by the movement of the mobile body within thechamber 8 upon the retardation of the vehicle.

If the vehicle is moving toward the left as viewed in the drawing themobile body within the chamber 8 will tend to move toward the leftagainst the abutment 9 as the rate of retardation of the vehicleincreases. When the rate of retardation reaches a predetermined valuethe follower plate I2, associated with the diaphragm abutment 9, willengage the stem 2'! of the pilot valve 25, and, upon a sumcient furtherincrease in the rate of retardation of the vehicle to overcome the forceof the spring 28, will force the pilot valve 26 from its seat againstthe bias of the spring 28 to open communication from the chamber I8above the valve piston I 4 to the atmosphere through the pilot valvechamber I9, chamber 29 and exhaust port 2l, thus rapidly decreasing thepressure within the chamber I8. Upon this decrease in the pressure onthe upper side of the piston Ill, the pressure within the chamber I6, onthe underside of the valve piston I fl, will raise the valve pistonupwardly, unseating the valve 23 and permitting the release of iluidunder pressure from the brake cylinder I, and brake cylinder pipe 5,through passage Il, chamber I 6, and exhaust port 25 to the atmosphere,to reduce brake cylinder pressure and thus reduce the rate ofretardation of the vehicle.

As the rate of retardation of the vehicle is thus reduced, the force ofinertia upon the mobile body within the chamber 8 is correspondinglydecreased, thus reducing the force exerted by the follower plate I2 onthe valve stem 2'I, and permitting the valve 26 to be seated by thespring 28 to close communication between the chamber I8 and theatmosphere, and to permit the pressure within the chamber I8 to build upby further ow of fluid under pressure from the chamber I6 through theport 3l in the valve piston I4. The valve 23 is thus forced to its seatby the combined pressure of the spring 22 and the increasing fluidpressure within the chamber I8 on the upper side of the piston Ill,acting against the fluid pressure within the chamber I6, thus preventingthe further decrease in uid pressure within the brake cylinder I.

As the Vehicle speed decreases, and the rate of retardation of thevehicle increases, due to the increasing coeiicient of friction betweenthe moving parts at lower vehicle speeds, the force of the mobile bodywithin the chamber 8 will again become sufficient to cause the followerplate I2 to act against the stem 2l with sufficient force to unseat thepilot valve 26 and repeat the above described operation of the valvepiston 24 to permit the further flow of fluid under pressure from thebrake cylinder I to the atmosphere. This operation of the relay valvepiston I4 may reoccur frequently during the deceleration of the vehicleuntil the pressure within the brake cylinder and within the chamber I8has been reduced to a value such that the force of the spring 22 on thevalve piston Id will hold the valve 23 seated when the pressure in thechamber I8 has been reduced to atmospheric pressure. The minlmumpermissible brake cylinder pressure is thus provided by the adjustmentof a spring 22.

If, when the brakes are applied, the vehicle is moving toward the right,as Viewed in the drawing, the force of the mobile body within thechamber 8 will be eiective against the abutment I I to force thefollower plate I3 against the valve stern 33 and unseat the pilot valve32 to vent the chamber I8 and cause operation of the relay pilot valvepiston I4 in the same manner as described above.

It will be apparent from the above description that I haveV provided areliable and inexpensive retardation controller for application to thebrake cylinder pipe of fluid pressure brake equipments that is operablein either direction of vehicle travel and that is not subject toadjustment by the operator during operation of the vehicle.

Many modications in the arrangement of parts r will be apparent to oneskilled in the art without departing from the spirit of my invention andI do not wish to be limited otherwise than by the scope of the appendedclaims.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. In a brake equipment for vehicles, in combination, a brake cylinder,means including a brake cylinder pipe for supplying fluid under pressureto said brake cylinder to apply the brakes, a retardation ,controllerdevice adapted to be mounted on said brake cylinder pipe adjacent saidbrake cylinder, a relay valve comprising a piston normally biased toclose communication between said brake cylinder and the atmosphere, andmeans for controllingrthe operation of said relay valve to effectcommunication between said brake cylinder and said atmosphere comprisingfluid inertia responsive means responsive to the rate of retardation ofthe vehicle and pilot valve means subject to a predetermined movement ofsaid inertia means in either direction from a neutral position.

2. In a brake equipment for vehicles, in combination, a brake cylinder,means including a brake cylinder pipe for supplying fluid under pressureto the brake cylinder to apply the brakes, a retardation controlleddevice adapted to be mounted on a iiange constituting an outlet in saidbrake cylinder pipe adjacent said brake cylinder, a relay valvecomprising a piston normally biased to close communication between saidbrake cylinder and the atmosphere, means for controlling the operationof said relay valve to effect communication between said brake cylinderand the atmosphere comprising means responsive to a desired rate ofretardation of the vehicle including a fluid mobile body, an abutmentactuated by said mobilefbody in either direction from a neutralposition, and means controlled thereby for effecting the operation ofsaid relay valve means to release fluid under pressure from` the brakecylinder.

3. In a brake equipment for vehicles, in combination, a brake cylinder,means for supplying fluid under pressure to the brake cylinder to applythe brakes, a retardation device for limiting the brake cylinderpressure comprising a chamber in constant open communication with thebrake cylinder, a relay valve device therein normally closingcommunication between the brake cylinder and the atmosphere, a chambersubstantially filled with a mobile body and having movable abutmentsforming the front and rear walls thereof, pilot valve means actuatedupon movement of said abutments by said mobile body in response to therate of retardation of the vehicle for operating said relay valve deviceto release fluid under pressure from said brake cylinder.

4. In a brake equipment for vehicles, in combination, a brake cylinder,means for supplying fluid under pressure to said brake cylinder to applythe brakes, a retardation controller device comprising a spring weightedvalve piston normally biased to close communication between said brakecylinder and the atmosphere, and subject on one side to brake cylinderpressure, means for equalizing the fluid pressure on opposite sides ofthe piston, a chamber substantially filled with a mobile inertia bodyand having movable abutment walls on the opposite sides thereof alignedin the direction of vehicle travel, means including pilot valvescontrolled by said movable abutment for unbalancing the pressures on thetwo sides of said valve piston to operate said valve piston to effect areduction in brake cylinder pressure.

5. In a brake equipment for vehicles, in combination, a brake cylinder,means for supplying fluid under pressure to said brake cylinder to applythe brakes, a retardation controller device comprising a spring weightedvalve piston normally biased to close communication between said brakecylinder and the atmosphere, a chamber substantially filled with amobile inertia body and having movable abutment walls on the oppositesides thereof in the line of vehicle travel, means controlled by saidmovable abutments for operating said spring weighted valve piston toelect a reduction in brake cylinder pressure upon movement of saidmobile body from the neutral position.

6. In a brake equipment for vehicles, in combination, a brake cylinder,means for supplying fluid under pressure to said brake cylinder to applythe brakes, and fluid inertia means movable in either of two directionsin accordance with the retardation of the vehicle, two valve means oneof which is actuated by movement of the inertia means in one direction,and the other of which is actuated by movement of said inertia means inthe other direction for effecting the release of fluid under pressurefrom the brake cylinder upon a predetermined rate of retardation of thevehicle.

7. In a brake equipment for vehicles, in combination, a brake cylinder,means for supplying fluid under pressure to said brake cylinder to applythe brakes, a retardation controller device comprising a spring weightedvalve piston normally biased to close communication between said brakecylinder and the atmosphere, and subject on one side to brake cylinderpressure, means for equalizing the fluid pressure on opposite sides ofthe piston, a fluid inerti-a body movable in either of two directionsfrom a neutral position in accordance with the retardation of thevehicle, and two pilot valves, actuated, respectively, upon movement ofsaid inertia body in the one or the other direction from said neutralposition for unbalancing the pressure on the two sides of said valvepiston to operate said valve piston to effect a reduction in brakecylinder pressure.

8. A vehicle brake equipment comprising, in combination, a brakecylinder, a pipe through which fluid under pressure is supplied to thebrake cylinder to eiect application of the brakes, said pipe having a Toutlet therein, a casing having a single extension detachably connectedto the said pipe at the T outlet, said extension constituting the onlymeans of attachment of the casing to the pipe, said casing also havingaV chamber constantly subject to the pressure of uid in said pipethrough a passage which extends through said extension, a normallyclosed valve operative to open said chamber to atmosphere andaccordingly release fluid under pressure from said pipe and brakecylinder, and inertia means contained within the casing and responsiveto the rate of retardation of the vehicle for controlling operation ofthe said valve.

9. A vehicle brake equipment comprising, in combination, a brakecylinder effective upon the supply of fluid under pressure thereto tocause application of the brakes, a normally closed exhaust valveoperative to release fluid under preslsure from the brake cylinder, acasing having a chamber, a body of fluid contained in said chamber,movable abutments located at opposite ends of said chamber in the lineof travel of the vehicle and moved by the inertia force of the fluidbody exerted thereon upon application of the brakes, and means operatedby the movement of said abutments for effecting operation of the saidvalve to release fluid under pressure from the brake cylinder.

10. A vehicle brake equipment comprising, in combination, a brakecylinder eiective upon the supply of uid under pressure thereto to causeapplication of the brakes, a normally closed exhaust valve operative torelease fluid under pressure from the brake cylinder, a casing having achamber, a body of fluid contained in said chamber, movable abutmentslocated at opposite ends of said chamber in the line of travel of thevehicle and moved by the inertia force of the fluid body exerted thereonupon application of the brakes, and means operative upon a certainuniform degree of movement of either of said abutments from its normalposition for effecting operation of said valve to release fluid underpressure from brake cylinder.

BURTON S. AIKMAN.

